In a number of arts, prior-art workers have found it necessary to provide devices for supporting heavy loads, with the nature of the device being such that the load must be transferred between two members connected together by fastening means in such manner that the fastening means transfers the load from one member to the other. Such a need is commonly met, for example, in well tools used to run, orient and land long and very heavy strings of pipe or tubing. Many types of fastening means have been employed in such devices, including screw threads, latch dogs or segments, no-lead fixed segments brought into engagement by relative rotation, and piston-actuated locking rings or segments. Such prior-art devices have achieved success and are commonly used. However, the loads to be supported continually increase, as for example with the increasing depth of oil and gas wells now being drilled, and the amount of space available for the components of the device has tended to decrease, so that there has been an increasing need for improved fastening means in well tools and like devices.